The Nucleic Acid Facility has been continuously approved and funded by the NCI since 1984. The availability of both routine oligonucleotide synthesis and the ability to consult on and perform innovative synthesis projects makes this core highly valuable to Cancer Center members. Ponzy Lu, PhD, Professor of Chemistry, has dir4ected this Shared Resource since its inception. Xiaolin Zhang, PhD, has served as Technical Director since 1994. At the time of the last competitive renewal, the Facility received "excellent to outstanding" merit. The Nucleic Acid Facility has remained at the forefront of synthetic technology through leadership and scientific expertise of Drs. Lu and Zhang. The Directors assist researchers by exploring novel avenues of oligonucleotide modification and nucleic acid derivatives for basic science as well as translational research applications. This contribution is best exemplified in the Nucleic Acid Facility's inclusion as a core resource in a recently-funded NCI Program Project Grant to explore the effects of antisense oligonucleotides (Gewirtz, PI), and the use of its scientific and technical expertise to supply fluorinated gancyclovir for use as a PET probe in order to track in situ gene expression by gene therapy vectors (Eck and Alavi) Total facility usage has increased 152% during the current project period. Usage by Cancer Center members has increased 296%. The percentage of usage by Cancer Center members has also increased, from 47% in 1993 to 75% in 1998, and the percentage of usage by Cancer Center members with peer-reviewed funding has increased, from 33% in 1993 to 74% in 1998.